TRANSPORTATION
Urban connection Designing a curved girder bridge in downtown Nashville. By: Diane Regensburg, P.E.
Division Street is an unlikely name for a new extension bridge in Nashville, Tenn., meant to break down neighborhood divides and improve connectivity in the city’s urban core. The four-lane approach and structure opened to traffic in October 2017, but the ribbon- cutting was held a month later with a ceremony led by Mayor Megan Barry. It runs six blocks from 8th Avenue South to 2nd Avenue South, providing a critical link between the booming Gulch district and the South Broadway (SoBro) community. It also provides easier access for downtown drivers to major transportation arteries such as Interstate 40. The extension bridge is multi-modal, accommodating not just vehicles but also bicyclists and pedestrians, many of whom arrive by Greyhound bus at the station a few feet away. As Nashville’s population continues to skyrocket — an average of 90 people per day move to the city — and congestion worsens, more people are considering alternative transportation modes. In such a high-traffic area, the social and environmental benefits of making the Division Street extension bridge multi-modal were clear. Challenges in an urban environment What was less clear, however, was the best approach for designing the project within a crowded urban setting. Multiple buildings encroached into the ideal route for the bridge and many others were close enough to be negatively impacted. Finding a way to snake the bridge through the path of least resistance was likened to threading a needle. The team and the client, Metro Nashville Public Works, knew these constraints would present both technical challenges and economic obstacles, so they set about developing a two-pronged solution. Buy-in and buyouts Early on, the team determined that a curved bridge would affect the fewest number of buildings and business. But a robust community engagement plan was necessary to support positive outcomes for those individuals, organizations, and businesses that would be impacted. The design team began by working with appraisers to assess the property, then they joined Metro Nashville’s property group for extensive conversations and negotiations with property owners. In the end, several major buyouts were required. A tire building and a garage that would have run underneath the bridge had to be acquired and subsequently demolished, as a recent Nashville ordinance prohibits buildings from being located below bridges due to the risk of fire. Some of these businesses were able, with buyout funds, to relocate to a new part of the city. The city had already bought out two previous locations from the tire and garage business. This time, the buyout allowed the owner to close up shop for good. The team also reconstructed a loading dock belonging to one affected business. The primary challenge, however, was the nearby Greyhound station. The project required acquisition of part of the Greyhound property being used for passenger pickup and drop-off parking as well as package drop-offs. The team was able to negotiate with Greyhound and modify the bridge design to help reach a solution. But the project also required acquisition of a small but successful market across from the station. The team worked with the shop owner to relocate his market within the remaining property, because a move to a new part of the city would have jeopardized his predominantly Greyhound passenger customer base.
The new Division Street Bridge links the booming Gulch district and the South Broadway community in Nashville and provides easier access to major transportation arteries. Photo: Aerial Innovations
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csengineermag.com
april 2018
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